Precursor solution for copper-zinc-tin-sulfur thin film solar cell, preparation method therefor, and use thereof

Abstract

Disclosed are a precursor solution for a copper-zinc-tin-sulfur (CZTS) thin film solar cell, a preparation method therefor, and the use thereof. The present invention discloses two types of simple metal complexes which are capable of formulating a high-quality precursor solution.

What is claimed is: 
     
         1 . A precursor solution for CZTS thin film solar cell, wherein
 the precursor solution is prepared by using a DMSO or a DMF as a solvent, and a precursor compound as a solute;   the precursor compound is composed of metal complexes, a metal salt and a thiourea,   wherein the metal complexes are a copper complex formed by a copper salt, and a thiourea or thiourea derivative, and   a tin complex formed by a tin salt, and a DMF or DMSO, and   the metal salt is a divalent zinc salt; and   the precursor compound is dissolved in the solvent of the DMSO or DMF to obtain a stable, clear and transparent precursor solution,   the copper complex is a complex formed by a copper salt, and a thiourea or derivative, including a complex of Cu(Tu) 3 X formed by a copper halide and a thiourea, wherein X is a halogen element including F, Cl, Br, and I,   the formed copper complex includes Cu(Tu) 3 Cl, [Cu 2 (Tu) 6 ]Cl 2 .2H 2 O, and Cu(Tu) 3 Br,   the formed copper complex further includes a complex of Cu(DMTu) 3 Br, Cu(TMTu) 3 Cl, and [Cu(ETu) 2 Br] 2  formed by a copper halide and a thiourea derivative, wherein the DMTu is N, N-dimethylthiourea, the TMTU is tetramethylthiourea, and the Etu is ethylene thiourea; and   the formed copper complex further includes a complex of Cu 4 (Tu) 10 (NO 3 ).Tu.3H 2 O formed by a copper nitrate salt and a thiourea;   the tin complex is selected from one or more of Sn(X) y Cl 4 , Sn(X) y F 4 , Sn(X) y Br 4 , Sn(X) y I 4 , and Sn(X) y (CH 3 COO) 4 , X is selected from one of DMSO, DMF, ethanol, and N-methylpyrrolidone, and y is a natural number greater than zero; and   a specific method for preparing the precursor solution is: taking DMSO or DMF as the solvent, dissolving the copper complex and the tin complex, the zinc salt and the thiourea directly into the solvent, to obtain the clear and transparent precursor solution.   
     
     
         2 . The precursor solution for the CZTS thin film solar cell according to  claim 1 , wherein the zinc salt is a divalent zinc compound, including but not limited to zinc halide, zinc acetate, zinc nitrate, and zinc sulfate. 
     
     
         3 . The precursor solution for the CZTS thin film solar cell according to  claim 1 , wherein in the precursor solution, a ratio of an amount of the thiourea to an amount of a copper element is not greater than 1. 
     
     
         4 . The precursor solution for the CZTS thin film solar cell according to  claim 1 , wherein in the precursor compound,
 a ratio of an amount of a copper element to an amount of a tin element is (1.5 to 2.5):1;   a ratio of an amount of a zinc element to the amount of the tin element is (0.9 to 1.5):1; and   a ratio of an amount of a sulfur element to a sum of the amounts of the copper element, the tin element and the zinc element is (1.0 to 6.0):1.   
     
     
         5 . The precursor solution for the CZTS thin film solar cell according to  claim 1 , wherein in the precursor solution,
 a concentration of a copper element in the solution is 0.05 mol/L to 5 mol/L;   a concentration of a tin element in the solution is 0.05 mol/L to 5 mol/L;   a concentration of a zinc element in the solution is 0.05 mol/L to 5 mol/L; and   a concentration of a sulfur element in the solution is 0.15 mol/L to 5 mol/L.   
     
     
         6 . The precursor solution for the CZTS thin film solar cell according to  claim 1 , wherein methods for preparing the copper complex and the tin complex are as follows:
 synthesizing the copper complex:   dissolving the thiourea in deionized water, adding, after the thiourea is completely dissolved, the copper salt to the solution, wherein a ratio of an amount of the added thiourea to an amount of the added copper salt is 3:1, and a temperature of the solution during the reaction is 70° C.; filtering, after dissolving the copper salt, the solution, holding the solution stand still, cooling the solution slowly, precipitating crystals of the target-product copper complex from the solution, and taking out and drying the crystal product; and   synthesizing the tin complex:   taking a tetravalent tin salt in a round-bottomed flask, sealing a mouth of the flask, taking the organic compound solvent DMF or DMSO and injecting the solvent into the flask, wherein a ratio of an amount of the organic compound in the solvent to an amount of the tin salt is 2 to 20; reacting the tin salt with the DMF or the DMSO solvent to generate a large amount of white precipitates, cleaning the precipitates with ethanol and drying the precipitates to obtain the corresponding target-product tin complex.   
     
     
         7 . Use of the precursor solution for the CZTS thin film solar cell according to  claim 1  in preparing a CZTS solar cell, wherein a method for preparing the CZTS solar cell includes following steps:
 (1) spin-coating the prepared precursor solution on molybdenum glass, heating, and annealing to produce a CZTS precursor thin film; 
 (2) heating the precursor thin film in an atmosphere of Se to carry out a selenization reaction, by replacing S atoms, partially or entirely, with Se atoms to produce a CZTSSe thin film material; 
 (3) taking out the CZTSSe thin film obtained after the selenization reaction and immersing the CZTSSe thin film in ultrapure water, and then placing the CZTSSe thin film in a water-jacketed beaker containing ammonia water, cadmium sulfate and thiourea solution, carrying out the reaction under heating, and depositing a layer of CdS on a surface of the CZTSSe thin film; 
 (4) sequentially sputtering, by a magnetron sputtering technology, ZnO and ITO on the surface of the sample in Step (3) as a window layer; and 
 (5) evaporating, by a thermal evaporation method, metal Ni and Al on the surface of the sample obtained in Step (4) as a cathode. 
 
     
     
         8 . Use of the precursor solution for the CZTS thin film solar cell according to  claim 2  in preparing a CZTS solar cell, wherein a method for preparing the CZTS solar cell includes following steps:
 (1) spin-coating the prepared precursor solution on molybdenum glass, heating, and annealing to produce a CZTS precursor thin film; 
 (2) heating the precursor thin film in an atmosphere of Se to carry out a selenization reaction, by replacing S atoms, partially or entirely, with Se atoms to produce a CZTSSe thin film material; 
 (3) taking out the CZTSSe thin film obtained after the selenization reaction and immersing the CZTSSe thin film in ultrapure water, and then placing the CZTSSe thin film in a water-jacketed beaker containing ammonia water, cadmium sulfate and thiourea solution, carrying out the reaction under heating, and depositing a layer of CdS on a surface of the CZTSSe thin film; 
 (4) sequentially sputtering, by a magnetron sputtering technology, ZnO and ITO on the surface of the sample in Step (3) as a window layer; and 
 (5) evaporating, by a thermal evaporation method, metal Ni and Al on the surface of the sample obtained in Step (4) as a cathode. 
 
     
     
         9 . Use of the precursor solution for the CZTS thin film solar cell according to  claim 3  in preparing a CZTS solar cell, wherein a method for preparing the CZTS solar cell includes following steps:
 (1) spin-coating the prepared precursor solution on molybdenum glass, heating, and annealing to produce a CZTS precursor thin film; 
 (2) heating the precursor thin film in an atmosphere of Se to carry out a selenization reaction, by replacing S atoms, partially or entirely, with Se atoms to produce a CZTSSe thin film material; 
 (3) taking out the CZTSSe thin film obtained after the selenization reaction and immersing the CZTSSe thin film in ultrapure water, and then placing the CZTSSe thin film in a water-jacketed beaker containing ammonia water, cadmium sulfate and thiourea solution, carrying out the reaction under heating, and depositing a layer of CdS on a surface of the CZTSSe thin film; 
 (4) sequentially sputtering, by a magnetron sputtering technology, ZnO and ITO on the surface of the sample in Step (3) as a window layer; and 
 (5) evaporating, by a thermal evaporation method, metal Ni and Al on the surface of the sample obtained in Step (4) as a cathode. 
 
     
     
         10 . Use of the precursor solution for the CZTS thin film solar cell according to  claim 4  in preparing a CZTS solar cell, wherein a method for preparing the CZTS solar cell includes following steps:
 (1) spin-coating the prepared precursor solution on molybdenum glass, heating, and annealing to produce a CZTS precursor thin film; 
 (2) heating the precursor thin film in an atmosphere of Se to carry out a selenization reaction, by replacing S atoms, partially or entirely, with Se atoms to produce a CZTSSe thin film material; 
 (3) taking out the CZTSSe thin film obtained after the selenization reaction and immersing the CZTSSe thin film in ultrapure water, and then placing the CZTSSe thin film in a water-jacketed beaker containing ammonia water, cadmium sulfate and thiourea solution, carrying out the reaction under heating, and depositing a layer of CdS on a surface of the CZTSSe thin film; 
 (4) sequentially sputtering, by a magnetron sputtering technology, ZnO and ITO on the surface of the sample in Step (3) as a window layer; and 
 (5) evaporating, by a thermal evaporation method, metal Ni and Al on the surface of the sample obtained in Step (4) as a cathode. 
 
     
     
         11 . Use of the precursor solution for the CZTS thin film solar cell according to  claim 5  in preparing a CZTS solar cell, wherein a method for preparing the CZTS solar cell includes following steps:
 (1) spin-coating the prepared precursor solution on molybdenum glass, heating, and annealing to produce a CZTS precursor thin film; 
 (2) heating the precursor thin film in an atmosphere of Se to carry out a selenization reaction, by replacing S atoms, partially or entirely, with Se atoms to produce a CZTSSe thin film material; 
 (3) taking out the CZTSSe thin film obtained after the selenization reaction and immersing the CZTSSe thin film in ultrapure water, and then placing the CZTSSe thin film in a water-jacketed beaker containing ammonia water, cadmium sulfate and thiourea solution, carrying out the reaction under heating, and depositing a layer of CdS on a surface of the CZTSSe thin film; 
 (4) sequentially sputtering, by a magnetron sputtering technology, ZnO and ITO on the surface of the sample in Step (3) as a window layer; and 
 (5) evaporating, by a thermal evaporation method, metal Ni and Al on the surface of the sample obtained in Step (4) as a cathode. 
 
     
     
         12 . Use of the precursor solution for the CZTS thin film solar cell according to  claim 6  in preparing a CZTS solar cell, wherein a method for preparing the CZTS solar cell includes following steps:
 (1) spin-coating the prepared precursor solution on molybdenum glass, heating, and annealing to produce a CZTS precursor thin film; 
 (2) heating the precursor thin film in an atmosphere of Se to carry out a selenization reaction, by replacing S atoms, partially or entirely, with Se atoms to produce a CZTSSe thin film material; 
 (3) taking out the CZTSSe thin film obtained after the selenization reaction and immersing the CZTSSe thin film in ultrapure water, and then placing the CZTSSe thin film in a water-jacketed beaker containing ammonia water, cadmium sulfate and thiourea solution, carrying out the reaction under heating, and depositing a layer of CdS on a surface of the CZTSSe thin film; 
 (4) sequentially sputtering, by a magnetron sputtering technology, ZnO and ITO on the surface of the sample in Step (3) as a window layer; and 
 (5) evaporating, by a thermal evaporation method, metal Ni and Al on the surface of the sample obtained in Step (4) as a cathode.